Honda — Spark Plug Check/Adjustment
Maintenance
From a Honda service manual covering: EB4000, EB5000, EB6500, EM4000SX, EM5000SXK3, EM6500SXK2. Check it applies to your exact model before use.
Applies to: Honda EB4000, Honda EB6500, Honda EM4000SX, Honda GX270T2 engine, Honda GX390T2 engine
Before you start
- If engine has been running, allow it to cool before proceeding.
Procedure
- Remove spark plug cap, then spark plug using spark plug wrench.
- Visually check; replace if heavily fouled or insulator cracked.
- Measure plug gap with wire-type feeler gauge.
- Adjust gap by bending side electrode.
- Install spark plug finger-tight, then tighten 1/8 – 1/4 turn.
- Install spark plug cap securely.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- SPARK PLUG: BPR5ES FridayParts $9.83 (NGK) W16EPR-U Amazon eBay $20.00 NAPA $2.53 (DENSO)
- PLUG GAP: 0.7 – 0.8 mm (0.028 – 0.031 in)
Full service-parts list: Honda EB6500 →, Honda EM4000SX →, Honda GX390T2 engine →
Source: Honda service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.